Case length....what happens if i don't trim my cases?

[phillips321]

Hi all,

I hate trimming my cases, it's probably the worst job of reloading and i need to trim, then chamfer the inside and outside, and measure length again.

If my cases are 0.005thou over SAMMI is that a problem? Just what can go wrong?

I understand that different neck lengths can possibly cause varying tension on the projectile but from a safety perspective what risks are there? If too long can the brass touch the lands?

Thanks in advance

 

[plonker]

No problemo at 0.005.
Never trim my cases.

 

[beanieboy]

I hear a lot about trimming cases and how best to do it. My Lyman express does all....chamfer, deburr, trim, uniform/clean primer pocket etc, so it's hardly a chore. Fact is though, I rarely need to trim my cases as they rarely stretch beyond recommend case length. This includes 22 hornet brass that many consider particularly prone to 'stretching.

 

[Fabnosh]

I neck size (popcorn out for that one) and do the occasional case length check but I genuinely can't remember the last time I had an issue and needed to trim.

FN

 

[Woodsmoke]

I use a Lee trim die and deluxe trimmer for all my cases. I never measure them, they all just get done as a matter of course. The Lee trim die won't let you trim below SAAMI spec' in any case, and if they don't need it no material is taken off. It only takes seconds per case, including inside and outside chamfers

The brass will never touch the lands. Worst case scenario is that the neck will tighten on the bullet and you'll get a pressure spike. You'll know if this is happening though, as your bolt will almost certainly be hard to close as you chamber a round (and open if you unload without firing)

 

[Foxyboy43]

Frequency of trimming is largely down to whether you load “hot” or not. Personally I never do load to the upper end and as late as yesterday reloaded some .308 which after firing had stretched only one or two thou and were still 14/15 thou below recommended length. However after neck sizing they had added a further couple of thou to their length but still well within tolerances. So in my particular case I don’t usually need to trim BUT call me old fashioned, and on the basis that manufacturers go to the bother of prescribing case lengths, I ALWAYS measure before and, if necessary after, trimming. If you do not you may eventually end up with the case neck mouth touching and at best creating loading problems or at worst a pressure spike because the brass has nowhere to stretch/flow - something you really do not want to happen a few inches from your nose, unless of you are in to multiple anaesthetics and facial reconstruction! Sooo - IMHO after cleaning, always examine each case carefully, both externally and internally for splits, insipient case separation and primer pocket fit, then resize, measure carefully and if required trim, then measure again. Measuring will take you seconds and trimming not an awful lot longer but you can then be confident that you and anyone near you are safe. Simples! Stay safe.

 

[Muir]

Jam a bit of the neck into the leade and see what happens.
Not trimming cases that are over length is foolish. ~Muir

 

[Foxyboy43]

Further to my earlier post - just happened to be checking something and from Richard Lee, who only wrote the reloading book, I quote:-
“cases that are too long will pinch the bullet and cause excessive pressure. Just because the cartridge easily enters the chamber it does not mean the case is not too long. The clearance created by the crimp allows the case to chamber, however when the bullet tries to open the case mouth it cannot, because the mouth is beyond the end of the chamber into the start if the bore. Be sure to trim your cases.”
The bold text is Richard Lee’s so all those on this thread would do well to heed his (and Muir’s) advice - whether you crimp or not. Be careful chaps.

 

[User00036]

Foxy, I know you reload for a .222, do you crimp them?

 

[jcampbellsmith]

Jam a bit of the neck into the leade and see what happens.
Not trimming cases that are over length is foolish. ~Muir

Yes, watched a Blaser owner blow primers one day because of this. Had to ask him to cease fire.
Regards
JCS

 

[Foxyboy43]

Foxy, I know you reload for a .222, do you crimp them?

Spooky!!! I am still rereading bits of Lee’s book and have just read the section on crimping!! In answer to your questions - yes and yes!
I have been reloading for rifle and pistol more years than I can remember and have always followed Lee’s advice which basically says always crimp:-
* if you full length resize;
* for revolver bullets;
* for bullets for magazines; and
* if you hunt.
The reasons given are to prevent recoil impacting on the length of the remaining bullets and to provide consistent pressures at ignition and thus improved accuracy. I would also add that on the odd occasion (really?) that you get your reloading wrong the crimp might prevent an unfired poorly seated bullet from sticking on extraction, thus spilling powder everywhere and reminding you to always bring a cleaning rod! Although I cannot find the bit in his book right now, I recall (dangerous at my age) that he says something like even a firm crimp will add only a few 100 lbs of pressure which in a full bore cartridge rated for perhaps in excess of 50,000 units is insignificant.
Finally and for clarity, I do not restrict my crimping to only cannelured bullets - the Lee Crimping Die will create its own cannelure and neither I nor any fox/deer have ever noticed an adverse impact on accuracy though some more experienced and necessarily demanding target shooters may have a different view. In any event if you load to your particular chamber length it is likely that those bullets with a pre-formed cannelure will leave the cannelure well clear of the case anyhow.
Finally, finally - crimping consistency will only be achieved if you trim your cases to the same length - see earlier thread from this morning.

ps
after crimping I test my bullets neck tension/crimp by inserting the bullet tip into a small hole on my bench (to save tip damage) and firmly pushing the case - before confirming overall length, call me old fashioned but this extra step takes 2 seconds per bullet and can avoid very annoying problems in the field. Okay, maybe I should have just stopped this post at “yes and yes”!!!
Hunkered down, helmet on, chin strap tightened. Incoming!!!!!

 

[25 Sharps]

Jam a bit of the neck into the leade and see what happens.
Not trimming cases that are over length is foolish. ~Muir

At least someone knows what they are talking about!

 

[njc110381]

At least someone knows what they are talking about!

It's one of the basics. Everyone should know this if they make their own ammunition.

 

[phillips321]

Foxy, I know you reload for a .222, do you crimp them?

Yes, watched a Blaser owner blow primers one day because of this. Had to ask him to cease fire.
Regards
JCS

Typically it's my Blaser R93 .222 that needs the cases trimming. I full length resize which often means i need to trim .001-003 thou off everytime, which i guess will eventually lead to a case head separation? I've always been told to FL resize for a blaser so lets not go down that rabbit hole.

I guess i need to do some trimming then, FYI the .005 example in my opening post was just a worst case, not actually what they are.

 

[User00036]

Thanks for that Foxy. after fl sizing with Redding standard die, & redding standard seating die I find that my bullets are plenty tight enough, can't even get them out with a vice & pliers! Also to avoid crimping I have to back the seating die off 1 turn, & then the top of shell holder doesn't make firm contact with the die. I like to feel that cam pressure clunk, but not possible with this arrangement. Slight irregularities in coal, but whether it makes a difference to accuracy I'm not sure. Apologies to OP if this is taking this off topic ? Thanks.

 

[phillips321]

And just to update my cases was 1.681 after firing, and after FL resizing it was 1.690

 

[Stalker62]

And just to update my cases was 1.681 after firing, and after FL resizing it was 1.690

 

[Foxyboy43]

Thanks for that Foxy. after fl sizing with Redding standard die, & redding standard seating die I find that my bullets are plenty tight enough, can't even get them out with a vice & pliers! Also to avoid crimping I have to back the seating die off 1 turn, & then the top of shell holder doesn't make firm contact with the die. I like to feel that cam pressure clunk, but not possible with this arrangement. Slight irregularities in coal, but whether it makes a difference to accuracy I'm not sure. Apologies to OP if this is taking this off topic ? Thanks.

A pleasure - sure isn’t that why we are all here?
Not sure though why you are getting slight irregularities in length - is that measuring to ogive or tip? The latter is very much dependent on consistent bullet length which especially with soft points can be very variable.

 

[Foxyboy43]

Typically it's my Blaser R93 .222 that needs the cases trimming. I full length resize which often means i need to trim .001-003 thou off everytime, which i guess will eventually lead to a case head separation? I've always been told to FL resize for a blaser so lets not go down that rabbit hole.

I guess i need to do some trimming then, FYI the .005 example in my opening post was just a worst case, not actually what they are.

Hmmm. Best not to let it lead to separation rather far better to detect it beforehand! If it does happen you will know - for a number of reasons and invariably it will happen when you are far from anywhere and almost certainly curtail that day’s stalking.
Your pre-loading brass check should always include looking for signs of a very fine (sometimes bright) line or even a crack running around the case usually just above the web (base). Earlier signs can be detected by a bent paperclip with the point sharpened and run this up the case several times - any hesitation will indicate early ICS and if I were you - bin any such cases immediately. I usually do this immediately after resizing as any embryonic failures will likely be exaggerated as part of that stretching/compressing process - others do it beforehand - your call but do it! There are earlier threads dealing with this in detail including making a little tool for this and even pictures for the hard of thinking! The attached illustrates in one picture this highly undesirable occurrence. Try the search facility for the thread but if no joy do let me know.
Good luck and stay safe.

 

[PeterH]

Jam a bit of the neck into the leade and see what happens.
Not trimming cases that are over length is foolish. ~Muir

Very much +1 on that. No doubt the OP has not been loading long so why teach someone bad habits. Most reloaders load not to save money but to form accurate rounds. With good case prepping attempting to make each case a clone of the other is the basics of making consistent ammunition.